Читать книгу Essentials of Veterinary Ophthalmology - Kirk N. Gelatt - Страница 86

Blood–ocular barriers contain endothelial and epithelial tight junctions with varying degrees of “leakiness.” These barriers prevent nearly all protein movement and are effective against low molecular weight solutes such as fluorescein and sucrose. The complexities of these structures differ between the various vascular beds, which allow movement of some substances from one compartment to the other. The two primary barriers within the eye are the blood–aqueous barrier (BAB) and the blood–retinal barrier (BRB). With inflammation, these barriers may be compromised, and allow fibrin and other proteins into the ocular tissues and space. Other minor barriers of the eye exist as well. The zonula occludens of the corneal epithelium prevents the movement of ions and therefore fluid from the tears into the stroma, prevents some evaporation, and protects the cornea from pathogens. The partial obliteration of the intercellular spaces provided by the macula occludens of the corneal endothelial cells prevents bulk flow of AH into the corneal stroma but allows moderate diffusion of small nutrients and water.